What to send a factory for a CNC quotation
A quotation is a guess until the factory knows seven things. When a buyer sends one PDF and asks for a price, the number that comes back is either padded to cover the unknowns or wrong. Neither helps either side.
The seven inputs
- Geometry — a 3D file. STEP is the safe default. STL loses the feature definitions, and a PDF drawing alone means somebody has to remodel your part before quoting it.
- Material and grade. "Stainless" is not a specification: 303, 304 and 316L machine at different rates and cost different amounts. 6061 and 7075 behave differently too.
- Tolerance, on the features that need it. See the tolerance note on this site for how to write it.
- Finish. As machined, bead blast, anodise (and which type), passivation, plating, laser mark. Finish is often 15–25% of the piece price and it is the item most often left out.
- Quantity — annual and per release. A 50-piece order and a 50,000-piece annual requirement are different processes, not different prices.
- Inspection and documentation. Do you need a dimensional report per batch, a material certificate, a first-article report, PPAP? Each is a line item.
- Delivery point and Incoterm. FOB Xiamen and DDP Chicago are not comparable numbers.
File formats that survive the trip
3D: STEP (.step/.stp) is the safest. SolidWorks, IGES and STL are accepted. 2D: PDF for reading, DWG or DXF for anything with a tolerance or a thread callout, because a scanned PDF cannot be measured.
One thing worth checking before you send: does the 3D model match the 2D drawing? When they disagree, the factory quotes the model and machines the drawing, or the reverse, and the argument starts at first article. We flag the conflict and ask which one governs. Cheaper to settle it by email.
What happens when something is missing
We quote anyway, with the assumption written down. "Quoted in 304, as-machined, ±0.05 mm general tolerance, no inspection report" is a usable quote because you can see what it does and does not include. A single number with no assumptions is not.
The assumptions are also where the surprises live. If the quote assumes 304 and you needed 316L, the price moves 30–40%. If it assumes as-machined and you needed anodising, it moves again.
What comes back, and when
Send a complete package and we return a quote within 24 hours, with the process route, the tolerance we will hold, the lead time for sample and for production, and the assumptions. If a feature is not manufacturable as drawn we say so and propose a change before quoting, rather than quoting a part we cannot make.
Email the drawing to xiamenyuhaoxin@163.com, or send it through the form on the contact page. STEP, DWG, DXF, PDF and native SolidWorks files all open here.